During the preparation of this document, the present inventors have become aware of the following prior United States patents and literature article:
______________________________________ Patentee Pat. No. Issue Date ______________________________________ Dinzl 2,244,420 June 3, 1941 De Boysson 2,253,112 August 19, 1941 Mercier 2,290,479 July 21, 1942 Adams et al 2,355,357 August 8, 1944 Stephens 2,453,732 November 16, 1948 MacDuff 2,551,274 May 1, 1951 Spannhake et al 3,237,406 March 1, 1966 Gendron et al 3,881,557 May 6, 1975 ______________________________________
"Dual floating pistons give more bang for buck," Product Engineering, Oct. 12, 1970, page 75.
Although these suggest that it is known to use accumulators in conjunction with pile drivers, our invention makes use of the accumulators in a different way. These others use the fluid to drive a piston attached to a weight, or a piston combined with a weight and use the accumulators merely to dampen the flow.